Process for the separation and purification of metals and metallic alloys



Patented Dec. 30, 1930 PATENT OFFICE ALBERT HANAK, OF PHILADELPHIA, PENNSYLVANIA PROCESS FOR THE SEPARATION AND PURIFICATION OF METALS AN D METALLIC ALLOYS No Drawing.

7 One of the objects of this invention is to separate the constituents of metallic alloys from each other in the metallic state. More specifically it relates to the separation of antimony in the metallic state from its alloys with either lead or tin, or both.

Another object of the invention is to adjust or lower the antimony content of antimony alloys to any desirable amount.

A further object of the invention is the purification of lead, tin, or lead tin alloys containing antimony as an impurity.

Heretofore the separation of antimonying therefore determined the amount of antimony present, it is possible to remove any part of the antimony by adding only that proportion of sodium corresponding to the quantity ofantimony to be removed. The alldy or compound of sodium and antimony so formed, has ahigher melting point than the remaining metal, and the 5 greater part of it rises to the surface of the liquid metal in form of a slump, when the metal' is sufficiently cooled down. However, the crust or slump is intermixed with large .quantities of metal, and the molten metal 40 underneath this crust or slump continues to hold in solution a quantity of the antimonyalkali metal compound or alloy. I have further discovered that if the metal, treated as described, is mixed with molten caustic alkali while the temperature of the metal is above the melting point of the caustic alkali, the antimony-alkali compound will dissolve in it, and the resulting solution rises to the surface, from which it can easily be drawn off, thereby obtaining a substantially complete Application filed August 8, 1928. Serial No. 298,405.

separation or the antimony sodium com pound from the remaining metal or alloy.

In carrying out the invention, the metal or alloy to be treated is melted in an ordinary kettle or some other suitable vessel, heated approximately 200 C. or more'above its melting point, the alkali metal which ordinarily is sodium on account of its relative cheapness, is stirred into the metal. The quantity of sodium added is predetermined by a chemical analysis. After the sodium has been well admixed with the metal, the temperature of the metallic bath is somewhat Y lowered, suflicientcaustic alkali such as caustic soda isstirred in to dissolve the antimony sodium alloy. The amount of caustic soda used is approximately four times the weight of the antimony extracted. The caustic soda sodium antimony alloy melt is run oil, allowed to cool, and then treated. The treat- .ment consists of washing it with a minimum quantity of water necessary to dissolve the caustic soda, and to react with the sodium in the sodium antimony compound to form the hydroxide. The antimony is liberated in the metallic state. The caustic solution is decanted or filtered. The solution is evap'- orated to dryness, and the dry caustic soda recovered is used over and over again. Excess of caustic soda resulting from the metal-= licsodium may be electrolyzed to obtain metallic sodium, or otherwise is disposed of. 'The following is a specific example of the process. .A quantity of solder metal, 10,000

pounds in weight analyzing 35% tin, 00%

lead, and '5% antimon was heated to 450 -C., and 200-i p ounds 0 sodium were stirred in. After lowering the temperature to 275 C., 2 000 pounds of caustic soda were thoroughly mixed with the metal. The caustic soda melt wasdrawn off, allowed to cool, and treated with allons of water. The metal was again ana yzed and showed an antimony content of 2%. The antimony recovered from the caustic solution amounted to 530 pounds, and analyzed 92% antimony.

I claim:

1. The process of separating antimony from lead alloys which comprises treating the alloy with an alkali metal to form a less fusible alloy of antimony and alkali metal dissolving same in caustic alkali in the molten state, separating the caustic melt and treating it with water thereby separating antimony in the metallic state.

2. The process of separating antimony from lead alloys which comprises treating the alloy with sodium and caustic soda to -form a less fusible alloy of antimony and sodium dissolving same in caustic soda in the molten state, separating the caustic melt and treating it with water thereby separating antimony in the metallic state.

3. The process of separating antimony from alloys containing tin which comprises treating the alloy with an alkali metal to form a less fusible alloy of antimony and alkali metal dissolving same in caustic alkali in the molten state, separating the caustic melt and treating it with water thereby separating antimony in the metallic state.

4 The process of separating antimony from alloys containin tin-which comprises treating the alloy wit-1 sodium and caustic soda to form a less fusible alloy of antimony and sodium dissolving same in caustic soda in the molten state, separating the caustic melt and treating it with water thereby separating antimony in the metallic state.

5. The process of separating antimony from alloys containing tin and lead which comprises treating the alloy with an alkali metal to. form a less fusible alloy of antimony and alkali metal dissolvingsame in caustic alkali in the molten state, separating the caustic melt and treating it withwater thereby separating antimony in the metallic state. 6. The process of separating antimony from alloys containing tin and lead which comprises treating the alloy with sodium and caustic soda to form a less fusible alloy ofantimony and sodium dissolving same in caustic soda in the molten state, separating the caustic melt and treating it with water thereby separating antimony in the metallic state.

ALBERT HANAK. 

